The present invention relates to absorbent articles, and more particularly to absorbent articles having a wetness indicator.
Various types of moisture or wetness indicators have been suggested for use in absorbent articles. Certain of these wetness indicators have been formed of compositions that are liquid soluble or liquid dispersible. These liquid soluble indicators rely on the dispersion of the composition upon contact with liquid to signal that liquid is present.
One difficulty associated with present absorbent articles containing a liquid soluble wetness indicator is that the wetness indicator composition may not disperse sufficiently. In particular disposable absorbent articles, for example, the wetness indicator composition can be placed on the interior surface of a moisture barrier so that the composition is visible through the moisture barrier prior to activation. Upon contact with liquid, the composition should disperse sufficiently so that the wetness indicator composition is no longer visible through the moisture barrier. Unfortunately, however, the liquid soluble wetness indicator compositions in present absorbent articles do not disperse thoroughly or rapidly enough to be completely invisible through the moisture barrier. A portion of the composition can remain visible, making the wetness indicator appear smudged. Not only is this undesirable from an aesthetic perspective, but it can also create confusion as to whether the indicator is signaling the presence of liquid in the absorbent article.
In response to the discussed deficiencies associated with prior absorbent articles, an absorbent article incorporating a liquid soluble wetness indicator has been developed that minimizes the likelihood of smudges appearing after activation. Various masking techniques can be used in combination with the wetness indicating graphic to lessen the degree to which the wetness indicator composition is able to be seen through the outer cover after contact with liquid.
Hence, in one embodiment, the invention concerns an absorbent article that includes an outer cover having in interior surface and an opposite exterior surface, and an absorbent assembly disposed on the interior surface of the outer cover. The absorbent article also includes a liquid soluble fading graphic that is disposed on the outer cover and in liquid communication with the absorbent assembly, and a masking graphic that is disposed on the outer cover and at least partially peripherally surrounding the fading graphic.
In another embodiment, the invention concerns an absorbent article that includes an outer cover having in interior surface and an opposite exterior surface, and an absorbent assembly disposed on the interior surface. A liquid soluble fading graphic is disposed on the outer cover and in liquid communication with the absorbent assembly, and a liquid soluble masking graphic is disposed on the outer cover and superposed on the fading graphic.
In a further embodiment, the invention concerns an absorbent article that includes an outer cover having in interior surface and an opposite exterior surface, and an absorbent assembly disposed on the interior surface. A first graphic formed of a liquid soluble composition is disposed on the outer cover and in liquid communication with the absorbent assembly. A second graphic formed of a liquid soluble composition is also disposed on the outer cover. The absorbent article further includes a permanent masking graphic that is disposed on the outer cover at least partially peripherally surrounding the first graphic and superposed on the second graphic. In particular embodiments, the absorbent article can also include a liquid soluble masking graphic superposed on the first graphic.
The term xe2x80x9cfading graphicxe2x80x9d is used herein to refer to a graphic that becomes invisible or becomes significantly less visible when exposed to urine. Suitable fading graphics comprise compositions such as inks that are soluble in aqueous solutions such as urine. The wetness indicating composition is positioned in the absorbent article so that it becomes wet and dissolves when the product is insulted with liquid. Once dissolved, the wetness indicating composition washes away from the outer cover and is obscured by the outer cover. As a result, the fading graphic seems to disappear from view.
Suitable urine-soluble inks are available from a variety of commercial vendors, such as Sun Chemical Corp. of Philadelphia, Pa. USA under the trade designation AQUA DESTRUCT. Particular urine-soluble compositions are disclosed in U.S. Pat. No. 4,022,211 issued May 10, 1977 to Timmons et al., which is incorporated herein by reference. The ink color can be selected to provide a pleasing appearance and graphic impact, including fading rapidly upon contact with liquid. To facilitate rapid fading, the fading graphics can comprise line drawings having a line width of from about 1 to about 2 millimeters.
The absorbent article can also include on or more permanent graphics, which for diapers and training pants may provide the caregiver with a greater opportunity to interact with the child. The term xe2x80x9cpermanent graphicxe2x80x9d is used herein to refer to a graphic that does not substantially change its degree of visibility when the absorbent article is insulted with urine, in simulated use conditions. The change in visibility of a graphic or a portion of a graphic can be determined based on a person""s observation of the graphic before and after the article containing the graphic is exposed to liquid. For purposes hereof, an article is exposed to liquid by immersing the article completely in an aqueous solution containing 0.9 weight percent sodium chloride, used at room temperature (≅23xc2x0C. ), for a period of twenty minutes. After 20 minutes the product is removed from the aqueous solution and placed on a TEFLON(trademark) coated fiberglass screen having 0.25 inch openings, which is commercially available from Taconic Plastics Inc., Petersberg, N.Y., USA, which in turn is placed on a vacuum box and covered with a flexible rubber dam material. A vacuum of 3.5 kilopascals (0.5 pounds per square inch) is drawn in the vacuum box for a period of 5 minutes, after which the article is removed and observed. The person with normal or corrected vision of about 20-20 should make the observations from a distance of 1 meter in an environment providing 30 footcandles (320 Lux) of illumination. Changes: in the visibility of the graphic should be identified, and distinguished where necessary from changes in the color of other materials such as fluff pulp within an absorbent assembly. Desirably, the permanent graphic can be configured so that the entire graphic also does not substantially change its appearance, size or shape when the product is insulted with liquid or exposed to the environment.
The term xe2x80x9cmasking graphicxe2x80x9d is used herein to mean a graphic adapted to obscure the visibility of a fading graphic after the fading graphic comes into contact with a liquid. The masking graphic can in particular embodiments, comprise a permanent graphic, comprise a graphic that is liquid soluble, or comprise both a permanent graphic and a graphic that is liquid soluble. The general term xe2x80x9cgraphicxe2x80x9d is used herein to mean: any design, pattern, or the like that is or becomes visible on an absorbent article, and specifically includes text messages that consist of one or more alphanumeric symbols, pictorial images that consist of one or more pictures, and combinations thereof; and, in relation to a masking graphic, any design, pattern, or the like that is disposed on a substrate with the result of obscuring the visibility of an associated graphic after contact with liquid.
The masking graphic is suitably formed with a color that matches colors of surrounding materials or permanent graphics of the absorbent article. For example, the masking graphic can be substantially the same color as the outer cover, substantially the same color as the absorbent assembly, or the like. In one particular embodiment, the masking graphic is white in color, which may be particularly advantageous because the outer cover and absorbent assembly in many commercially available disposable absorbent articles are white.
In use, the active graphic can appear or fade when an accident occurs and urine comes into contact with the active graphic. Desirably, the active graphic appears or fades in about 3 minutes or less, particularly in about 1 minute or less, and more desirably in about 20 seconds or less, when the absorbent article is insulted with 200 milliliters or more of urine, and, more desirably about 40 to about 60 milliliters or more of urine.
Permanent graphics can be positioned anywhere on the outer cover, and in particular embodiments can desirably be positioned in the front waist region along or near the longitudinal centerline of the product. Particular arrangements for permanent and wetness indicating graphics are disclosed in U.S. patent application Ser. No. 09/333,223, filed on Jun. 15, 1999 by Cammarota et al. and titled xe2x80x9cAbsorbent Articles Having Wetness Indicating Graphics Incorporating A Training Zone,xe2x80x9d now U.S. Pat. No. 6,307,119 B1 granted Oct. 23, 2001, and U.S. patent application Ser. No. 09/333,222, filed on Jun. 15, 1999 by Olson et al. and titled xe2x80x9cAbsorbent Articles Having Wetness Indicating Graphics Providing An Interactive Training Aid,xe2x80x9d now U.S. Pat. No. 6,297,424 B1 granted Oct. 2, 2001.
The fading graphics can but need not necessarily be positioned closer to the transverse centerline of the product than the permanent graphics. In particular embodiments, the fading graphics are positioned between the transverse centerline of the product and the permanent graphic so as to be properly focussed and not hidden from view during use. Locating the fading graphics in the crotch region of the product, near the target spot for urination, can also assist with rapid exposure of the fading graphic to urine upon insult. It is desirable to locate fading graphics on the area of the outer cover that is most likely to experience wetness during the first void. Of course, alternative positioning of the permanent and fading graphics are possible, such as the permanent graphic in the crotch region and the fading graphic in one of the waist regions, both permanent and fading graphics in one or both of the waist regions and/or the crotch region, or the like. The fading graphics can but need not necessarily be positioned on one or more sides of the permanent graphics, such as xe2x80x9cfloatingxe2x80x9d under the permanent graphic. Alternatively, the permanent graphic can surround the fading graphic and vice versa.
In one particular embodiment, all of the fading graphics are located in a distinct active graphic region where the child can focus attention. The active graphic region suitably has a length dimension measured parallel to the longitudinal centerline of about 10 centimeters, more particularly about 9 centimeters, and a width dimension measured parallel to the transverse centerline of about 6 centimeters. The active graphic region can, for instance, be spaced from the first end edge of the product by approximately 13 to 16 centimeters.
There can be one or more fading graphics. It is believed desirable to use a plurality of fading graphics in order provide the greatest impact to the caregiver and/or child. In particular embodiments, a training pant comprises 3 or more fading graphics, particularly from 4 to 8, such as 5 arranged in a 2-1-2 pattern.
The size of the fading graphics may depend in part on their number and type. It is generally preferred that the fading graphics have a size of at least about 1.5 by 1.5 centimeter and less than about 3 by 3 centimeters, and particularly at least about 1.8 by 1.8 centimeter and less than about 2.5 by 2.5 centimeters.
The overall size of the permanent graphic can be significantly larger than the overall size of each discrete fading graphic. In particular embodiments, for instance, the permanent graphic has a size measured by overall surface area that is at least twice as large, and more particularly at least three times as large, as the size of a single fading graphic. The maximum length dimension of the permanent graphic, measured parallel to the longitudinal centerline, is desirably about 8 to about 9 centimeters.
The permanent and fading graphics are suitably disposed on the outer cover. The term xe2x80x9cdisposed onxe2x80x9d and variations thereof are intended to mean that one element can be integral with another element, or that one element can be a separate structure bonded to or placed with or placed near another element. Thus, the graphics can be formed or applied directly or indirectly to a surface of the outer cover, formed or applied between layers of a multiple layer outer cover, formed or applied to a substrate that is placed with or near the outer cover, formed or applied within a layer of the outer cover or another substrate, or other variations or combinations thereof. In particular embodiments, the graphics can be printed, sprayed, or otherwise applied directly on a layer of the outer cover. In other embodiments, the graphics can be applied to a layer placed with or near the outer cover, such as a substrate associated with the absorbent assembly, including but not limited to tissue layers, liquid handling layers, absorbent layers, or the like.
The permanent graphics can be located on, the exterior surface of the outer cover to enhance the visual impact of the permanent graphics. Alternatively, however, the permanent graphics can be located on the interior surface of the outer cover or between layers of a multilayer outer cover, provided the permanent graphics remain visible from the exterior of the Product.
The fading graphics can be located on the interior surface of the outer cover, which is particularly desirable for graphics that are triggered by urine in order to enhance the speed at which the graphics are contacted with urine and thus change their visual appearance. The outer cover desirably comprises a material that is formed or treated to be liquid impermeable. In alternative embodiments, the outer cover can comprise a material that is formed or treated to be at least partially liquid permeable. In this latter case, the fading graphics can be located between layers of a multilayer outer cover. Regardless of location, fading graphics should be visible from the exterior of the product before activation.
xe2x80x9cLiquid impermeablexe2x80x9d, when used in describing a layer or multi-layer laminate, means that a liquid, such as urine, will not pass through the layer or laminate, under ordinary use conditions, in a direction generally perpendicular to the plane of the layer or laminate at the point of liquid contact. Liquid, or urine, can spread or be transported parallel to the plane of,the liquid impermeable layer or laminate, but this is not considered to be within the meaning of xe2x80x9cliquid impermeablexe2x80x9d when used herein.
The outer cover can comprise a transparent or translucent material. Desirably the outer cover has sufficient opacity or is treated according to the methods disclosed herein to mask a urine soluble ink after it has dissolved. Such an outer cover should not be so opaque that the graphics printed on the interior surface of the outer cover or adjacent to the interior surface are obscured. Polymer films used to form the outer cover can be treated with titanium dioxide to make the film appear white and to develop sufficient opacity to mask urine, BM and dissolved inks. Examples of suitable outer cover materials include films formed of polyethylene, polypropylene, cataloy, bi-component, any polymer based extruded film, or the like. One such film is a polyethylene film having a thickness of about 0.02 millimeter (0.75 mil).
The permanent and fading graphics can be formed on or applied to the outer cover or another substrate bonded to or placed with or placed near the outer cover by any suitable technique. The graphics are desirably registered with other components of the absorbent article during manufacture such that the graphics are positioned in the desired regions of the product.
The fading graphics are suitably in liquid communication with the absorbent assembly of the product. As used herein, the term xe2x80x9cliquid communicationxe2x80x9d means that liquid such as urine is able to travel from one layer or element to another layer or element. The absorbent assembly can but need not include a slot or densified region, incorporate a liquid distribution layer, or the like, to channel or direct liquid to the location near the outer cover where the fading graphics are located.
It is theorized that migration of the dissolved wetness indicator composition away from the outer cover and into the absorbent assembly can improve the fading or disappearing quality of the graphics. To enhance this effect, the outer cover can be attached to the absorbent assembly in a windowpane design, whereby the fading graphic region of the outer cover is not bonded to the absorbent assembly and the regions of the outer cover surrounding the fading graphic region are bonded to the absorbent assembly. One suitable method and apparatus for adhesively bonding the outer cover to the absorbent assembly in a windowpane design is disclosed in U.S. Pat. No. 5,683,752 issued Nov. 4, 1997 to Popp et al., which is incorporated herein by reference.
Hence, in another embodiment, the invention concerns an absorbent article including an outer cover having in interior surface and an opposite exterior surface, and an absorbent assembly disposed on the interior surface. The absorbent article also includes a liquid soluble fading graphic that is disposed on the outer cover and in liquid communication with the absorbent assembly. The fading graphic is disposed in a fading graphic region and the absorbent assembly is bonded to the outer cover in regions other than the fading graphic region.
Absorbent articles suitable for use with the present invention include diapers, training pants, incontinence products, diaper pants, disposable underwear, medical garments, bandages, absorbent swimwear, wipes, or the like. Suitable training pants and diaper pants can have seamed side portions or refastenable side portions. The present invention is particularly suited for use with training pants or diaper pants to aid in toilet training. One particular training pant suitable for use with the present invention is disclosed in U.S. Pat. No. 4,940,464 issued Jul. 10, 1990 to Van Gompel et al., which is incorporated herein by reference. The van Gompel et al. patent describes various materials of which the training pant can be made, and a method of constructing a training pant. The training pant can also be constructed using the methods and apparatus disclosed in U.S. Pat. No. 5,766,389 issued Jun. 16, 1998 to Brandon et al., which is also incorporated herein by reference.